The present invention relates to a microhardness tester of the load rod assembly type.
Prior art load rod assemblies comprise a load rod to which an indenter is attached for impingement on a specimen to be tested for microhardness. These load rod assemblies have springs attached to the load rod to return the rod to a home position spaced apart from the test specimen. A disadvantage of this arrangement is that the weights applied to the load rod to move it and consequently the indenter onto the testing specimen must be calibrated to compensate for the spring load.
Other disadvantages of prior art load rod assemblies are the need for realigning optical objective elements when the indenters are changed to accommodate a new test scale and the relatively long amount of time required to achieve the necessary fine focus on the test specimen when only a single focus control is used. Additionally, there are standard test specifications which operators avoid in their hurry to complete certain tests.